Automatic flight sequence controller



April 1955 K. J. BULLEYMENT 2,706,239

AUTOMATIC FLIGHT SEQUENCE CONTROLLER Filed June 29, 1953 BEAM CENTERSELECTION BEAM CENTER L I23 r BEACON 12 E3? \'F /--ALT|TuoE m seouzuczINITIATION ll STARTING SWITCH 295 A A l X. INVENTOR. 2l6 FOLLOW 327 22kmKEITH J BULLEYMENT P j -;-'274 y $4) 326 ,1 SELECT I93 j ATTORNE YUnited States Patent AUTOMATIC FLIGHT SEQUENCE CONTROLLER Keith J.Bulleyment, St. Louis Park, Minn., assignor to Minneapolis-HoneywellRegulator Company, Minneapolis, Minn., a corporation of DelawareApplication June 29, 1953, Serial No. 364,868

Claims. (Cl. 340-345) This invention relates to the field of automaticcontrol, and more particularly to apparatus for controlling a pluralityof parameters of flight in accordance with the requirements ofsuccessive sections of an extended flight, including means forautomatically sequencing the ap paratus as the successive sections ofthe flight are completed. The broad general object of the invention isto provide improved apparatus of the class just described.

A more specific object of the invention is to provide an automaticsequencer in which prolonged operation of a starting switch cannotresult in multiple sequencing.

Another object of the invention is to provide apparatus of the classdescribed in which passage of a selector in the automatic sequencer overan energized contact in going to an unenergized contact cannot result inmultiple sequencing.

Another object of the invention is to provide control apparatus of thetype described which includes a telemetric system having alternativecontrolling and following conditions, and in which sequencing isprevented when said telemetric system is in said following condition oris being adjusted to control at a different control oint. p Yet anotherobject of the invention is to provide an automatic sequencer including aproportioning telemetric system and a homing type telemetric system forcontrolling the sequencing operation, in which the homing system isprevented from causing the sequencing operation while the proportioningsystem is in operation.

Various other objects, advantages, and features of novelty whichcharacterize my invention are pointed out with particularity in theclaims annexed hereto and forming a part hereof. However for a betterunderstanding of the invention, its advantages, and objects attained byits use, reference should be had to the subjoined drawing, which forms afurther part hereof, and to the accompanying descriptive matter, inwhich I have illustrated and described a preferred embodiment of myinvention. In the drawing:

Figure l is a schematic showing of the elements making up one embodimentof the invention, and of the preferred manner of interrelating theseelements to give the desired operation to the system as a whole, and

Figure 2 is a detail giving a second view of a record as used in Figure1.

The invention herein comprises an advance over known automaticsequencing systems, of which a typical example is to be found in thecopending apphcation of Oscar Hugo Schuck, Serial No. 266,699, filedJanuary 16, 1952, and assigned to the assignee of the presentapplication. In the Schuck application the operation of a plurality ofselectors is controlled by perforations in a continuous record, meansbeing provided for advancing the record in discrete steps upon theachievement of any one of a plurality of conditions selected by one ofthe selectors. I

The present invention shows a similar control record 10, driving meanstherefor generally indicated by the reference numeral 11, a pair ofhoming type telemetric systems 12 and 13, and a pair of proportioningtype telemetric systems 14 and 15. Record 10 controls the passage ofelectrical energy from a source 16 of unidirectional voltage indicatedas a battery, and from a source 17 of alternating voltage through atransformer 20 having a primary winding 21 and a secondary wrndlng 22,the latter being provided with intermediate taps 23, 24 and 25.

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As described in the copending Schuck application, record 10 may comprisea strip of heavy paper divided mto successive fields. Each field may beconsidered as divided mto unit areas, and a plurality of such areas maybe defined as a data group, the data being represented by the presenceor absence of perforations in the unit areas making up each data group.As an illustratron the data group for any number in the decimal systembetween 000 and 999 may comprise three rows of 10 unit areas, oneperforation in each row representing by its position a digit from 0 to9.

As an alternative illustration, arbitrary meaning may be given to eachof the unit areas in a data group: in the group reserved for beam centerselection later to be described a first area may represent the localizerbeam, a second area the glide path beam, a third the taxi beam, etc. Thesimplest arbitrary meaning which may be assigned to a single area isthat of on and off accordmg as the area is or is not perforated.

Readout means aligned with the control record must be provided tointerpret the data represented by the various groups. In the drawingthis function is shown schematically by mutually insulated contactelements 26, 27, 3 0, 31, 32, 33, 38, 39, 34, 35, 36, 37, 40 and 41 onone slde of record 10 and spring contact fingers 42, 43, 44, 45, 46, 47,48, 49, 50, 51, 52, 53, 54 and 55 on the other side of the record, butequivalent structures will of course occur to those skilled in the art.Perforations in the record are shown to permit engagement betweencontacts and 44, 33 and 47, and 51, and 41 and it is not attempted toshow the large number of perforations and contacts necessary toadequately perform with precision all the functions of a complete systemof this nature.

The drive means 11 for record 10 is shown to comprise a series wound,non-reversing direct current motor 56 including a stator winding 57 anda wound rotor 60 having brushes 61 and 62. The shaft 63 of motor 56 Idrives a suitable gear speed reduction unit 64, and the output shaft 65from unit 64 is connected to a sprocket or other wheel 66 arranged inengagement with record 10 to advance the latter with respect to thefixed and spring contacts, the latter rising out of the perforations inthe paper as it advances.

More perfected chart driving and contact lifting means adapted to use inthis structure are shown in a copending application of Raymond E.Michel, Serial No. 397,882 filed December 14, 1953, and assigned to theasslgnee of the present application. The intricacy of that structure isnot necessary to an understanding of the present invention, however, andaccordingly a simplified showing has been used herein.

To complete the description of drive unit 11 it is pointed out that ahoming disc 67 of electrically conducting material is mounted on shaft65. Disc 67 has a notch 70 in its periphery, and is continually engagedthroughout its rotation by a spring contact 71. A second spring contact72 engages the periphery of disc 67, in such a fashion that an electriccircuit is completed through disc 67 between contacts 71 and 72 exceptwhen notch 70 is aligned with contact 72. A capacitor 68 is connectedacross contacts 71 and 72 to prevent sparking.

Motor 56 is energized from battery 16 under the control of a motor relay73 shown to have a winding 74 which acts through an armature 75 todisplace a first movable contact 76 into engagement with a first fixedcontact 77, and to displace a second moveable contact 78 out of normalengagement with a second fixed contact 79. A capacitor 80 is connectedacross contacts 76 and 77 to prevent sparking.

Telemetric system 12 is shown to comprise a nonreversible direct currentmotor 81 whose shaft 82 carries a disc 83 of electrically conductivematerial notched at 84 and continuously engaged by a spring contact 85.Engaging the periphery of disc 84 are a plurality of spring contacts 86,87, and 90. The arrangement is such that electrical connection iscontinuously maintained between contact 85 and all of contacts 86, 87and 90 except when one of the latter is aligned with notch 84. Shaft 82is extending to actuate the movable contact 91 of a selector switch 92having fixed contacts 93, 94, 95 and 96. In

actual practice switch 92 has a complete circle of fixed contacts aroundit, most of which are omitted here for simplicity.

Associated with switch 92 are a plurality of normally open switches 97,98 and 100. Switch 97 is arranged to be operated by means indicated at101 when the localizer receiver indicates that the craft is on thecenter of the localizer beam. Switch 98 is arranged to be operated bymeans indicated at 102 when the glide path receiver indicates that thecraft is on the center of the glide path beam. Similarly switch isarranged to be operated by means indicated at 103 when a radio receiverindicates that the craft is on the center of a taxi beam. Devices ofthis nature are known and their details are of no concern to .thepresent invention.

Telemetric system 13 is shown to comprise a nonreversible direct currentmotor 104 whose shaft 105 carries a disc 106 of electrically conductingmaterial notched at 107 and continuously engaged by a spring contact110. Engaging the periphery of disc 84 are a plurality of springcontacts 111, 112 and 113. The arrangement is such that electricalconnection is continuously maintained between contact 110 and all ofcontacts 111, 112 and 113, except when one of the latter is aligned withnotch 107. Shaft 105 is extended to actuate the movable contact 114 of aselector switch 115 having fixed contacts 116, 117, and 121. In actualpractice switch 115 has a complete circle of fixed contacts associatedwith it, most of which are omitted here for simplicity.

Associated with switch 115 are a pair of normally open switches 122 and123. Switch 123 is arranged to be operated by means indicated at 125when the craft reaches a marker beacon. Switch 122 is arranged to beoperated by means indicated at 124 when the craft attains a selectedaltitude. Devices of this nature are known and their details are of noconcern to the present invention.

A normally open, momentary contact starting switch 126 is provided forputting the system in operation, and system operation is also controlledby a pair of relays 127 and 130. Relay 127 is shown to comprise awinding 131, which acts through an armature 132 to displace a movablecontact 133 out of normal engagement with a fixed contact 134.Associated with relay 127 to give slow action of the relay are acapacitor 135 and a resistor 136. Relay 130 is shown to comprise awinding 137 which acts through an armature 140 to displace a movailzlzcontact 142 into engagement with a fixed contact Relay 130 is energizedfrom source 17 through a rectifier 145 and through a lockout amplifier148 including a triode 146 having an anode 147, a control electrode 150,a cathode 151 and a heater 152 energized in a conventional fashion notshown. Associated with rectifier 145 is a filter capacitor 153, andassociated with triode 146 are a pair of cathode resistors 154 and 158,a variable grid resistor 155, a capacitor 156, and a rectifier network157 shown by way of illustration to comprise rectifiers 160, 161, 162,and 163.

Proportioning telemetric system 14 is shown to comprise an amplifier 164energized from source 17 and having output terminals 165 and 166.Amplifier 164 is supplied with a control signal through a cable 167. Theoutput of amplifier 164 energizes the amplifier phase winding of analternating current motor 171 having a rotor 172, mounted on a shaft173, and a line phase winding 174 with which is associated a quadraturecapacitor 175. Through shaft 173 and such reduction gearing, not shown,as may be desirable motor 171 drives a synchro transmitter 176 energizedfrom source 17 and supplying an output on conductors 177. The drive frommotor 171 is continued to operate balancing means in amplifier 164 so asto balance the signal on cable 167, as is well known.

The purpose of proportioning system 14 is to supply on conductors 177 asignal representative of a desired value of a condition which may varythrough a range: one example of such a condition is the heading of thecraft, which may vary through 360 degrees. The signal on conductors 177may be compared in conventional apparatus not shown with a signalrepresenting the actual heading of the craft, and the difference betweenthe signals may be used to operate the heading control surfaces of thecraft.

An output from amplifier 164 is supplied to network 157 through anisolating resistor 180.

Proportioning telemetric system 15 is shown to comprise an amplifier 181having input terminals 182 and 183 and output terminals 184 and 185.Amplifier 181 is supplied with a signal through one or more of aplurality of summing resistors 186, 187, 190, and 191 under the controlof a relay 192 having a winding 193 which acts through an armature 194to displace movable contacts 195, 196, 197, 200, and 201 out of normalengagement with fixed contacts 202, 203, 204, 205, and 206 and intoengagement with fixed contacts 207, 210, 211, 212, and 213. Associatedwith relay 192 are a signal cable 214, an isolating resistor 215, and aswitch 216 actuated by suitable means 217, under the control of record10 if desired.

Amplifier 181 energizes the amplifier phase winding 218 of analternating current motor 220 having a rotor 221, mounted on a shaft222, and a line phase winding 223 with which is associated a quadraturecapacitor 224. Shaft 222 is extended to operate the slider 225 of arebalance voltage divider 226 having resistance element 227 and theslider 230 of a selecting voltage divider 231 having a resistanceelement 232. A further voltage divider 233 is shown to have a resistanceelement 234 and a slider 235 actuated through a mechanical connection236 by an altimeter 237. Voltage dividers 231 and 233 together make upan electric bridge 238. Windings 232 and 234 are energized from source17 directly. Winding 227 is energized from source 17 through atransformer 240 having a primary winding 241 and a secondary winding242. If convenient secondary winding 242 may be a part of transformer20, rather than of the separate transformer.

The output from bridge 238 is supplied to utilization circuits through apair of transformers 243 and 244 having primary windings 245 and 246 andsecondary windings 247 and 250, all respectively.

As mentioned above, the invention as illustrated has been radicallysimplified to facilitate pointing out the inventive contributions. Inpractice not only do each of switches 92 and 115 have more contacts, butthere are more homing systems and more proportioning systems, the numberof each being limited only by the number of flight characteristics it isdesired to control, select, or monitor.

In one preferred embodiment of the invention the following values werefound satisfactory for the components listed:

Source 16 28 v. D. C. Source 17 115 v., 400 cycles, 1 phase. Resistor136 5,000 ohms. Resistor 154 100 ohms. Resistor 155 l5,000-25,000 ohms.Resistor 158 100 ohms. Resistor 100,000 ohms. Resistor 186 1,000,000ohms. Resistor 187 1,000,000 ohms. Resistor 190 1,000,000 ohms. Resistor191 1,000,000 ohms. Resistor 215 100,000 ohms. Resistor 227 05,000 ohms.Resistor 232 0l0,000 ohms. Resistor 234 040,000 ohms. Capacitor 68 .01microfarad. Capacitor 80 1 microfarad. Capacitor 135 100 microfarads.Capacitor 153 4 microfarads. Capacitor 156 4 microfarads. Capacitor 175.12 microfarad. Capacitor 224 .12 microfarad.

Operation Except for relay 130, the apparatus of Figure 1 is shown inthe condition it finally assumes in response to the illustratedperforations in record 10. Sources 16 and 17 are connected to supplyelectrical energy. Motors 56, 81, and 104 are inoperative so that discs67, 83 and 106 and switches 92 and 115 are as shown. Proportioningsystems 14 and 15 are balanced so that no signal voltages appear atoutput terminals 165 and 166 and output terminals 184 and 185, andmotors 171 and 220 are deenergized. Relays 73, 127, and 192 are asshown, and switches 97, 98, 100, 122, 123, 126, and 216 are open.Sliders 230 and 245 are equally spaced from the upper ends of theirresistance elements, and slider 225 is spaced from the right hand end ofits resistance element in the same proportion. Assume that the craft isin flight at 5000 feet altitude, which determines the position of slider235. The means whereby relay 130 is pulled in will now be explained.

It will be seen that grid 150 of triode 146 is grounded, at 275, throughresistor 155 and also at 276, through rectifiers 160 and 161 andrectifiers 162 and 163 of network 157. The network can be continued, asillustrated by conductors 278 and 279, to include further pairs ofrectifiers as the number of proportioning systems in the apparatus isincreased. The common point 277 between rectifiers 160 and 161 isconnected through conductor 280 and resistor 180 to terminal 165 ofamplifier 164: since proportioning system 14 is balanced, terminal 165is at ground potential. The common point 281 between rectifiers 162 and163 is connected through resistor 215, conductor 282, and relay contacts195 and 202 to ground bus 274. Accordingly grid 150 is at groundpotential.

The anode voltage for triode 146 is supplied at a terminal 283 fromsource 17, through conductors 251 and 284 and rectifier 145: therectified voltage is filtered by capacitor 153.

The anode circuit for triode 146 may be traced from terminal 283 throughconductor 285, relay winding 137, conductor 286, anode 147 and cathode151 of triode 146, conductor 287, resistor 154, and the winding of motor104 to ground connection 290: also connected to conductor 287 is afurther circuit including conductor 291, resistor 158, the winding ofmotor 81, and ground connection 292. The equivalent resistance betweencathode 151 and ground is sufficiently small that little self biasingtakes place, and triode 146 conducts, pulling in relay 130. A circuit iscompleted at contacts 142 and 144 which will presently be traced, andsuch additional pairs of contacts as are considered desirable may beprovided to control other1 output circuits such as that of proportioningsystem 5.

A circuit may be traced from source 17 through conductors 251, 252, and253, resistance element 234, and ground connections 254 and 255 back tothe source: from conductor 253 a further circuit may be traced to groundconnection 254 through resistance element 232. A bridge output circuitmay be traced from slider 230 through conductor 256, primary winding 245and conductor 257 to slider 235: primary winding 246 is connected inparallel with primary winding 245.

The output from proportioning system is taken from secondary winding 250through conductors 260 and 261. This output is designed to be suppliedto suitable altitude control apparatus, not shown, to determine thealtitude at which the craft flies, as is Well known in the art. Anysuitable means not shown may be provided to perform the switchingfunction of making the altitude control apparatus operative: under theconditions now being described this is not done, so that the altitude ofthe craft remains under manual or other control.

A circuit may be traced from the upper terminal of secondary winding 247through conductor 263, relay contacts 203 and 196, conductor 264,summing resistor 186, summation point 265, and conductor 266 to inputterminal 182 of amplifier 181, the circuit being completed from inputterminal 183 through ground connections 267 and 270. Summing resistors187, 190, and 191 are also connected to summation point 265, but theirother terminals are grounded through conductors 271, 272, and 273,moveable relay contacts 197, 200, and 201, and fixed relay contacts 204,205, and 206, all respectively, and ground bus 274, so that the signalfrom secondary winding 247 is the only one supplied to amplifier 181.

As long as sliders 230 and 235 are equally displaced downwardly alongtheir respective resistance elements, the signal supplied by secondarywinding 247 is zero. If the altitude of the craft changes, slider 235 ismoved with respect to resistance element 234 by altimeter 237, and asignal appears between sliders 230 and 235 and is transmitted bytransformer 243 to amplifier 181. Motor 220 is energized, operating in asense to move slider 230 in the same direction as slider 235 until thesliders are again aligned: bridge 238 is then balanced and operation ofmotor 220 is interrupted.

For normal vertical movements of the craft in response to its elevatordisplacement, slider 230 follows slider 235 so closely that the signalfrom transformer 243 is only slightly greater than the threshold voltageof amplifier 181. In strong vertical air currents or turbulent air, onthe other hand, it is possible for altimeter slider 235 to move fasterthan motor 220 can drive slider 230, so that temporary signals of somemagnitude can be supplied by transformer 244. Since the altitudecontroller has not been placed in operation, however, this has noundesirable effect on the control of the craft.

A circuit may now be traced from tap 25 of transformer 20 throughconductor 278, contacts 55 and 41 and cable 167 to amplifier 164, thecircuit being completed through ground connections 288 and 289.Amplifier 164 includes a set of summing resistors like those associatedwith amplifier 181, and the balancing arrangement actuated by shaft 173may be a voltage divider and a transformer energized from source 17,resembling units 226 and 240 discussed above. In the stable condition ofthe apparatus here assumed the balance condition has been reached, andan output has been supplied on conductors 177 suitable to adjust aheading controller not shown so that it maintains the heading of thecraft at 270, or due west, as an example. Transmission of the signalfrom synchro 176 may be controlled by any suitable switching means notshown and suitable further means are preferably provided forestablishing operation of the heading controller.

Except for the following movement of slider 230 as the altitude of thecraft changes, and for the operation of triode 146 and relay 130, theapparatus is in the condition illustrated in Figure l, and thiscontinues as the craft continues in flight. Two means are provided forchanging this state of affairs: one is an emergency measure, and theother is a part of the normal operation of the apparatus. The formerwill be discussed first, and is accomplished by the human pilot simplyby closing switch 126 momentarily. The effect of this is to advancerecord 10 so that a new field of data groups is aligned with the readoutmeans, and hence the switch should not be operated unless the succeedingfield carries data pertinent to the flight conditions presently desired.

Closure of switch 126 completes a circuit from the positive terminal ofsource 16 to positive bus 293, thence through conductor 294, switch 126,conductor 295, junction point 296, conductor 297, relay contacts 142 and144 now closed, conductor 300, relay contacts 133 and 134, conductors301 and 302, relay winding 74, and ground connections 303 and 304 to thenegative terminal of source 16. Relay 73 pulls in, completing a circuitfor motor 56 from positive bus 293 through conductor 305, relay contacts77 and 76, and conductor 306, the circuit being completed through groundconnection 307. Operation of motor 56 rotates disc 67 into engagementwith contact 72, completing a circuit from positive bus 293 throughconductor 310, contact 71, disc 67, contact 72, and conductors 311 and302 to relay winding 74. Switch 126 may now be released: operation ofmotor 56 through a complete cycle is ensured by homing disc 67.

It is conceivable that one not familiar with the apparatus mightmaintain switch 126 closed for a longer interval than that required fora cycle of operation of motor 56, in which event a second cycle ofoperation of the motor would be carried out. This would result in anunintended advance of record 10 beyond the field of data appropriate tothe location and condition of the craft, and would thus establish adangerous condition of continuing discoordination in the controlapparatus. To avoid this, relay 127 is provided. A circuit extends fromjunction point 296 through resistor 136 to winding 131 of relay 127 andto capacitor 135, the circuit being completed through ground connection312. When switch 126 is closed capacitor begins to charge exponentiallytoward a value determined by the voltage of source 16 and by therelation between the resistance of resistor 136 and the direct currentresistance of winding 131. The resistor and the winding cooperate toform a voltage divider, thus determining the steady state voltage acrosswinding 131. At some point in the charging curve of the capacitor thevoltage thereacross is sufficient to cause relay 127 to pull in, thusinterrupting at contacts 133 and 134 the circuit between switch 126 andrelay 73. The interval required to accomplish this is chosen, by properselection of components, to be greater than the interval required formotor 56 to drive disc 67 into engagement with contact 72, but smallerthan a complete cycle of operation of motor 56. Thus improper cyclingbecause of switch 126 being held down is prevented.

In normal operation of the apparatus switch 126 is operated briefly, foronly a short portion of the period of disc 67. If switch 126 is releasedbefore relay 127 pulls in, a circuit for the latter relay may be tracedfrom positive bus 293 through conductor 310, contact 71, disc 67,contact 72, conductors 311 and 301, relay contacts 134 and 133,conductor 300, contacts 144 and 142, conductor 297, and resistor 136.This circuit is interrupted when relay 127 operates, or when switch 126is released if this occurs later, and capacitor 135 discharges throughwinding 131. Since the resistance in the discharge path of the capacitoris less than that in the charging path, the capacitor discharges morerapidly than it charged, and the voltage across winding 131 quicklydrops below the value necessary to hold the relay in: when it drops outthe circuit through the contacts 133 and 134 to relay winding 74 isagain completed.

The foregoing description has been directed to the function of switch126, which is basically an emergency or starting component. flightcontinuing under the control of record 10 until the craft assumes apredetermined condition, which is shown in Figure l as passing over aradio beacon. This results in closure of switch 123 completing a circuitfrom positive bus 293 through the switch, conductor 313, contacts 117and 114 of switch 115, and conductor 314 to terminal 296, thusenergizing the circuit for motor relay 73 and slow acting relay 127described above, and motor 56 is again energized as before.

Operation of motor 56, whether by manual or automatic means, displacescontrol record 10 so that the field thereof shown in Figure 1 isreplaced by the one containing the data groups illustrated-in Figure 2and other groups. This second field of punchings has been prepared forcooperating with the readout contacts to call for flight of the craft ata controlled altitude of 1500 feet, with a heading of 0, until thelocalizer beam has been intersected. Perforations in the record nowallow engagement between contacts 42 and 26, 46 and 32, 48 and 38, 52and 36, and 54 and 40. It has been found helpful in realizing theinvention to introduce a resilient or lost motion connection betweendisc 67 and the record feeding means 66 so that the last degrees or soof rotation of disc 67 occur after the new field of datais in place.This allows certain functions about to be described to take place beforenotch 70 comes into alignment with contact 72 to deenergize motor 56:the circuit for relay 73 through switches 123 and 115 must be opened,for example.

A first circuit is completed, from positive bus 293, through readoutcontacts 42 and 26, disc contact 86, disc 83 and contact to motor 81,the circuit being completed through ground connection 292. The signal atcontact 85 is also transmitted through resistor 158 and conductors 291and 287 to cathode 151, making the latter positive with respect toground by an amount sulficient to cut off triode 146, and relay 130drops out, interrupting the circuit from junction point 296 to relaywinding 74 if it has not already been interrupted by relay 127.

When the readout contacts complete their engagement a further circuitcan be traced from positive bus 293 through readout contacts 52 and 36,disc contact 113, disc 106, and contact to motor 104, the circuit beingcompleted through ground connection 290. The voltage at contact 110 isalso transmitted through summing resistor 154 and conductor 287 tocathode 151, cooperating with that from resistor 158 to make the cathodepositive with respect to the grid. The two resistors are so chosen thatregardless of how many of motors 81 and 104 are energized, discharge ofthe triode is still cut off.

The choice of resistors 154 and 158 is also influenced by the fact thata circuit may be traced from contact 110 for example through resistor154, conductor 291, and resistor 158 to motor 81: if motor 81 is notenergized through disc 83, but motor 104 is energized through disc 106,the current in the circuit just traced must not be large enough to causeoperation of motor 81. The opposite relationship is also possible, andthe same precautions as to size of resistors 154 and 158 will preventimproper energization of motor 104 when motor 81 is energized.

A final consideration in determining the size of resistors 154 and 158is that they must be small enough so as not to introduce self biasing inthe triode circuit Normally this is not needed, theto the extent thatthe triode does not conduct sufficient current to actuate relay 130.

Operation of motor 81 displaces disc 83 to a point where notch 84 isaligned with contact 86, thus interrupting the motor energizing andtriode biasing circult through contact 85, and operation of motor 104(118- places disc 106 to a point where notch 107 is aligned with contact113, thus interrupting the motor energizing and triode biasing circuitthrough contact 110. If no other factors are acting, triode 146 nowconducts and relay 130 pulls in, partially reestablishing the sequencingcircuit to relay 73. Switch contact 91 has been moved into engagementwith contact 95, and switch contact has been moved into engagement withcontact and out of engagement with contact 117. This latter changeinterrupts the energizing circuit for relay 127 and the relay drops out,completing the reestablishment of the sequencing circuit for relay 73.

The perforation in record 10 allowing engagement between readoutcontacts 54 and 40 supplies a signal from transformer 20 throughconductor 318, the readout contacts, and cable 167 to amplifier 164:this supplies alternating voltage at output terminals 165 and 166 whichis transmitted to winding 170 of motor 171 by conductor 315 and groundconnections 316 and 317. The line phase winding 174 of motor 171 isenergized from source 17 through contacts 78 and 79, conductors 320 and321, quadrature capacitor 175, and ground connections 322 and 323. Motor171 operates in a sense to rebalance amplifier 164 through shaft 173,and to drive synchro 176 to give on conductors 177 a signalrepresentative of a heading of 0 degrees. The auxiliary function ofturning on the heading control is performed hereby suitable apparatusnot specifically shown.

As long as amplifier 164 remains unbalanced a voltage appears betweenterminal 165 of the amplifier and ground. When terminal 165 is negativea circuit may be traced from terminal 166 through ground connections 317and 275, variable resistor 155, conductors 324 and 325, rectifier 160,junction point 277, conductor 280 and resistor 180 to terminal 165.Capacitor 156 is connected between grid and ground to filter the signalsupplied across resistor 155. In the next half cycle, when terminal 165is positive, a further circuit may be traced from terminal 165 throughresistor 180, conductor 280, junction point 277, rectifier 161 andground connections 276 and 317 to terminal 166 of the amplifier. By thisexpedient rectifier 160 is prevented from being subjected to dangerouslyhigh inverse voltages.

Variable resistor constitues a threshold adjustment for the lockoutamplifier. It acts with resistor 180 as a voltage divider acrossterminals 165 and 166 of amplifier 164. The larger resistor 155 is, thegreater the portion of the amplifier voltage that appears on the grid.However the amplifier voltage includes not only the useful component,which is of the frequency of source 17 and of a selected phase, but alsoincludes noise such as out of phase components, components of doublefrequency, and so on. These noise components do not affect the motor,but are converted to a direct voltage signal by rectifier and capacitor156 and hence affect the triode. It is necessary to select such a valuefor resistor 155 that the unwanted or noise components of the amplifiersignal do not cut otf the triode: in order to accomplish this somesensitivity of the tube to the desired signal must be sacrificed.

It is found that the characteristics of the components making up thiscircuit change with ambient temperature, so that resistor 155 cannot begiven a fixed value, but must be adjustable as temperature changes ifoptimum operation at all ambient temperatures is to be obtained.

When grid 150 is driven to cutoff, triode 146 interrupts theenergization of relay 130 which accordingly drops out, disabling thesequencing circuit. It should be pointed out that motors 81 and 104 arerelatively quick acting, while motor 171 and also motor 220 are slowoperating. As a result the sequence circuit is normally controlled byrelay 130 rather than by relay 127, and by the grid signal on triode 146rather than the cathode signal: the complete circuit is howevernecessary for entire safety in operation of the system.

Since it is desired to control the altitude of the craft switch 216 isnow closed, and the altitude controller is energized through simpleswitching functions not illustrated. When switch 216 closes a circuit iscompleted from the positive terminal of source 16 through conductor 326,switch 216, conductor 327, relay winding 193, and ground connections 330and 304: relay 192 accordingly pulls in. A circuit may now be tracedfrom junction point 281 through resistor 215, conductor 282, relaycontacts 195 and 207, and conductors 331 and 332 to output terminal 184of amplifier 181: this circuit functions as described in connection withamplifier 164, resistor 180, and rectifiers 160 and 161.

Operation of relay 192 ungrounds summing resistors 187, 190, and 191 atcontacts 204, 205 and 206, and connects them instead through contacts211, 212, and 213, and cable 214 to readout contacts 31, 32, and 33.Figure 2 shows that contacts 32 and 46 are in engagement supplyingvoltage from transformer tap 24 through conductor 333 to contact 32 andhence through cable 214, relay contacts 212 and 200, conductor 272 andsumming resistor 190 to summation point 265. Sum ming resistor 186 isdisconnected from transformer 243 at relay contact 203, and is insteadconnected through relay contact 210 and conductor 334 to slider 225, thecircuit being completed through ground connections 335 and 267.

The inputs to amplifier 181 now come from transformer tap 24 and slider225. If these signals are not equal and opposite motor 220 operates,adjusting slider 225 to bring about this condition, and simultaneouslyadjusting slider 230, to change the bridge output voltage and supply asignal to the altitude controller. Slider 230 acts now as an altitudeselector: when the altitude of the craft has been changed sufficientlyto bring slider 235 into alignment with slider 230, by operation ofaltimeter 237, the bridge is again balanced, and the output onconductors 260 and 262 becomes zero.

It should be emphasized that slider 230 is driven at the speed of motor220 to a position determined by the punchings in the data group alignedwith contacts 31, 32 and 33. While motor 220 operates slowly incomparison with motors 81 and 104, it completes its operation in anexceedingly brief interval compared with that required for the aircraftto reach the desired altitude. Accordingly the voltage supplied fromterminal 184 of amplifier 181 continues for only a brief interval andthereafter remains zero until the record advances: in this configurationof the apparatus systems 14 and are alike, and conductor 331 could beconnected directly to conductor 282.

On the other hand, it was pointed out above that when relay 192 isdeenergized the output from amplifier 181 may have considerablemagnitude at any time, if the craft is subject to rapid changes inaltitude. If under these circumstances conductor 331 were connecteddirectly to conductor 282, triode 146 might be cut off at anyunpredictable time, and sequencing at a proper instant might easily beprevented. It is for this reason that conductor 331 goes through relay192 while conductor 280 does not.

As a result of the operation of motors 56, 81, 104, 171, and 220 acondition is reached in which switch contact 91 engages fixed contact95, switch contact 114 engages fixed contact 120, synchro 176 and slider230 are adjusted to select the heading and altitude called for by record10, and triode 146 maintains relay 130 energized. This continues untilthe craft reaches the center of the localizer beam, when radio means notshown functions to close switch 97. A circuit may now be traced frompositive bus 293 through switch 97, conductor 336, switch contacts and91, conductor 337, switch contacts and 114 and conductor 314 to junctionpoint 296, to initiate operation of motor relay 73 as described above,and the cycle of operation repeats itself.

The purpose of lockout amplifier 146 and relay 130 will now be apparent.Each field of data groups in record 10 represents a set of flightconditions which must be achieved concurrently. The changeover periodwhen the record is advanced is one in which different adjustments aretaking place at different rates, and in which a selection is being madeof what parameter is to be used to trigger the next sequencingoperation.

Switch 115 may pass over a contact connected to positive bus 293 ingoing toward a selected contact which is not so connected, or switch orswitch 96 may be engaging a contact which is connected to the positivebus when the new field of data groups becomes active. Any of theseevents could conceivably cause undesired resequencing of the record.Moreover a perceptible interval is required for proportioning systems 14and 15 to become balanced at new values, and it is undesirable toconnect the outputs of these systems to control the craft until thesystems have become balanced. The cathode and grid circuits of lockoutamplifier 146 are connected to be influenced by these conditions, andrelay is held in its deenergized position until the last of them hasbeen satisfied. Thereafter the relay is pulled in and sequencing can beinitiated automatically or manually.

From the foregoing it will be evident that I have invented improvedautomatic sequencing equipment in which multiple sequencing isprevented, whether due to improper manual operation or tocharacteristics of homing and proportioning systems included in theequipment.

Numerous objects and advantages of my invention have been set forth inthe foregoing description, together with the details of the structureand function of the invention, and the novel features thereof arepointed out in the appended claims. The disclosure, however, isillustrative only, and I may make changes in detail within the principleof the invention to the full extent indicated by the broad generalmeaning of the terms in which the appended claims are expressed.

I claim as my invention:

1. Apparatus of the class described comprising, in combination: a sourceof electrical energy; cyclic drive means to be energized from saidsource; first and second circuits connecting said drive means to saidsource; homing switch means in said first circuit. for maintainingenergization of said drive means through a full cycle of operationthereof once said cycle has been initiated; a plurality of groups ofcondition responsive switches in said second circuit connected to saidsource and closed on the occurrence of a plurality of conditions;selector switches in said second circuit connected severally to saidgroups of condition responsive switches for completing a circuit betweensaid drive means and any selected one of said condition responsiveswitch means; rapid acting motor means connected to said selectorswitches for causing operation thereof; manual switching means in saidsecond circuit connected to said source; slow acting relay means in saidsecond circuit and energized through said manual switching means, andthrough said condition responsive switch means and said selectorswitches, for interrupting said second circuit after it has beencompleted for a sufficient interval to permit operation of said homingswitch means to complete said first circuit; telemetric means forcausing operation of said motor means to adjust said selector switchesto desired settings, including a control record, having a series offields of data groups representative of a series of sets of concurrentdesired selecting states for said selector switches, and readout meansaligned with said record and connected to said source for energizingsaid motor means in accordance with the data contained in particularones of said groups; means connecting said drive means to said controlrecord so that each cycle of operation of said drive means replaces oneof said fields aligned with said readout means by a succeeding field,whereby said record may be advanced upon closure of a conditionresponsive switch selected by a data group in said record, and a newcondition responsive switch may thereupon be selected to causesubsequent advance of said record upon the occurrence of the conditionselected thereby; further selecting means adjustable through a range ofadjustments; slow acting motor means for adjusting said furtherselecting means; telemetric means including said control record forcausing operation of said slow acting motor means to adjust said furtherselecting means to any desired position within said range; and furtherrelay means in said second circuit connected to said further selectingmeans for operation during energization of said slow acting motor meansto interrupt said second circuit.

2. Apparatus of the class described comprising, in combination: a sourceof electrical energy; cyclic drive means to be energized from saidsource; first and second circuits connecting said drive means to saidsource; homing switch means in said first circuit for maintainingenergizaton of said drive means through a full cycle of operationthereof once said cycle has been initiated; a plurality of conditionresponsive switches in said second circuit connected to said source andindependently closed on the occurence of a plurality of conditions, sothat more than one of said switches may be closed at the same time; aselector switch in said second circuit connected to said conditionresponsive switches for completing a circuit to said drive means fromany selected one of said condition responsive switch means; rapid actingmotor means connected to said selector switch for causing operationthereof; slow acting relay means normally completing said second circuitand energizable through said condition responsive switches and saidselector switch to interrupt said second circuit after it has beencompleted for a sufficient interval to permit operation of said homingswitch to complete said first circuit; telemetric means for causingoperation of said motor means to adjust said selector switch to completesaid second circuit through any desired condition responsive switch,including a control record having a series of data groups representativeof a series of adjusted conditions of said selecting switch, readoutmeansaligned with said record and connected to said source forenergizing said motor means in accordance with the data contained in thedata groups aligned with said readout means, and means connecting saidcontrol record to said drive means so that each cycle thereof replacesthe data group aligned with said readout means by a succeeding group,whereby said record may be advanced upon closure of a conditionresponsive switch selected in accordance with the data of a first datagroup in said record, the succeeding data group may cause operation ofsaid selector switch to select a new condition responsive switch tocause subsequent advance of said record, said slow acting relaymaintaining said second circuit open after said motor means initiatesoperation of said selector switch for an interval suificient to allowsaid selector switch to select any condition responsive switch requiredby the data group now aligned with said readout means, so that if saidselector switch passes over a circuit connected to a closed conditionresponsive switch, in moving to a circuit connected to an open conditionresponsive switch, renewed operation of said drive means cannot beinitiated.

3. Apparatus of the class described comprising, in combination: aplurality of condition selecting devices each adjustable through a rangeof adjustment; means connected thereto for adjusting each of saiddevices to select any condition within its range; a control recordhaving a series of fields of data groups representative of a series ofsets of concurrent desired selecting states for said selecting devices;drive means connected to said control record for operation to advancesaid record by successive increments determined in magnitude by adimension of said fields; initiating means included among said selectingdevices for selecting a condition upon the occurrence of which operationof said drive means is to take place; readout means adjacent said recordand connected to said first named means and said drive means forconverting the data groups comprised in a field thereof aligned withsaid readout means to signals causing operation of said first namedmeans and said drive means determined by the data making up said groups;and switching means connected to at least one of said selecting devicesand in circuit with said drive means to prevent operation of said drivemeans from continuing for a second of said increments until thecondition selected by said initiating means, in accordance with a datagroup in the field presented to said readout means by a first of saidincrements, has been achieved.

4. Apparatus of the class described comprising, in combination: aplurality of condition selecting devices each adjustable through a rangeof adjustment; means connected thereto for adjusting each of saiddevices to select any condition within its range; a control recordhaving a series of fields of data groups representative of a series ofsets of concurrent desired selecting states for said selecting devices;drive means connected to said control record for operation to advancesaid record by successive increments determined in magnitude by adimension of said fields; initiating means included among said selectingdevices for selecting a condition upon the occurrence of which operationof said drive means is to take place; readout means adjacent said recordand connected to said first named means and said drive means forconverting the data groups comprised in a field thereof aligned withsaid readout means to signals causing operation of said first namedmeans and said drive means determined by the data making up said groups;manual means connected to said drive means and operable independently ofsaid initiating means to cause operation of said drive means; and meansincluding a slow acting relay connected to said manual means and incircuit with said drive means to prevent operation of said drive meansfrom continuing for more than one of said increments regardless of howlong said manual means remains operated.

5. Apparatus of the class described comprising, in combination: aplurality of condition selecting devices each adjustable through a rangeof adjustment; means connected thereto for adjusting each of saiddevices to select any condition within its range; a control recordhaving a series of fields of data groups representative of a series ofsets of concurrent desired selecting states for said selecting devices;drive means connected to said control record for operation to advancesaid record by successive increments determined in magnitude by adimension of said fields; initiating means included among said selectingdevices for selecting a condition upon the occurrence of which operationof said drive means is to take place; readout means adjacent said recordand connected to said first named means and said drive means forconverting the data groups comprised in a field thereof aligned withsaid readout means to signals causing operation of said first namedmeans and said drive means determined by the data making up said groups;manual means connected to said drive means and operable independently ofsaid initiating means to cause operation of said drive means; andswitching means connected to at least one of said selecting devices andsaid manual means and in circuit with said drive means to preventuninterrupted operation of said drive means for more than one of saidincrements.

6. Apparatus of the class described comprising, in combination: firstsignal means giving a first signal in accordance with the actual valueof a condition; second signal means adjustable to give a second signalin accordance with a selected value of the condition; motor meansconnected,to adjust said second signal means; motor control meansconnected to said motor for controlling the operation thereof inaccordance with an input signal; telemetric means for giving a firstinput signal for said motor control means, including a control recordhaving a series of fields of data groups, one group in each field beingrepresentative of a desired value of the condition, readout meansaligned with said record for supplying a signal in accordance with thedata in a data group comprised in said record, and drive means connectedto said record for energization to replace one of said fields alignedwith said readout means by a succeeding field; means connected to saidsignal means for supplying a second input signal for said motor controlmeans which varies in accordance with the difference between said firstand second signals; means connected to said second signal means forsupplying a third input signal for said motor control means which variesin accordance with the selected value of the condition; switching meansconnected to said motor control means, to the two last named means, andto said telemetric means, and having a normal condition in which saidmotor control means is supplied with said second input signal, and anoperated condition in which the motor control means is supplied withsaid first and third input signals; lockout means connected to saiddrive means and energizable to prevent energization of said drive means;and means, including said switching means in the operated conditionthereof, for energizing said lockout means from said motor controlmeans.

7. Apparatus of the class described comprising, in combination: acontrol record having a series of fields of data groups, each groupbeing representative of one of a series of desired values for one of aplurality of conditions; readout means adjacent said record forconverting to control signals the data groups comprised in a fieldthereof aligned with said readout means; drive means connected to saidcontrol record for operation to advance said record by successiveincrements determined in magnitude by a dimension of said fields; slowacting selecting means connected to said readout means for operation toselect values for a plurality of conditions in accordance with data in aplurality of said data group; means responsive to the actual value of afirst of said conditions; lockout means connected to said selectingmeans for preventing operation of said drive means until all theselecting means connected thereto have completed operation; switchingmeans connected to said condition responsive means, to said readoutmeans, and to the selecting means for said first condition and operablebetween a normal position in which said selector is connected to followsaid responsive means, and an operated position in which said selectoris connected for operation in accordance with said readout means; andmeans including said switching means in the normal position thereof fordisconnecting said lockout means from the selectlng means for said firstcondition.

8. Apparatus of the class described comprising, in combination: acontrol record; record driving means; record readout means; rapid actingmeans connected to said readout means for selecting, in accordance withdata read out from said record, one of a number of conditions achivementof which is to energize said drive means; slow acting means connected tosaid readout means for perform- 30 ing a further function in accordancewith data read out from said record; and means connected to said drivingmeans and said slow acting means, and operative while said slow actingmeans is in operation to prevent energization of said driving means.

9. Apparatus of the class described comprising, in combination: acontrol record; record driving means; record readout means; rapid actingmeans for selecting, in accordance with data read out from said record,one of a number of conditions achievement of which is to energize saiddrive means; slow acting means for performing a further function inaccordance with data read out from said record; and means connected tosaid driving means and said rapid acting means, and operative while saidrapid acting means is in operation to prevent energization of saiddriving means.

10. Apparatus of the class described comprising, in combination: acontrol record; record driving means; record readout means; rapid actingmotor means for selecting, in accordance with data read out from saidrecord, one of a number of conditions achievement of which is toenergize said drive means; slow acting motor means for performing afurther function in accordance with data read out from said record; andmeans connected to said driving means and said motor means, andoperative While either motor means is in operation to preventenergization of said driving means.

References Cited in the file of this patent UNITED STATES PATENTS2,612,331 Frazier et al. Sept. 30, 1952

